Rock Identifier
Labradorite ((Ca, Na)(Al, Si)4O8 (Plagioclase Feldspar)) — mineral
mineral

Labradorite

(Ca, Na)(Al, Si)4O8 (Plagioclase Feldspar)

Hardness: 6.0-6.5 on Mohs scale; Color: Gray to dark gray with iridescent 'schiller' flash in blue, green, and gold; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific Gravity: 2.68-2.72.

Hardness
6
Luster
Vitreous to pearly
Identified More mineral

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Physical properties

Hardness: 6.0-6.5 on Mohs scale; Color: Gray to dark gray with iridescent 'schiller' flash in blue, green, and gold; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific Gravity: 2.68-2.72.

Formation & geological history

Formed in igneous or metamorphic rocks, particularly basalt, gabbro, and norite. It crystallizes in mafic igneous rocks through slow cooling, often occurring in anorthosite massifs. Formation dates back hundreds of millions of years in various tectonic settings.

Uses & applications

Primarily used in jewelry as beads or cabochons, and as an ornamental stone for architectural projects (countertops/tiles). Often sought after as a specimen for metaphysical collections.

Geological facts

First discovered in Labrador, Canada, in 1770. It is famous for a unique optical effect known as 'Labradorescence,' caused by light diffracting within microscopic lamellae (layers) composed of different feldspar compositions.

Field identification & locations

Identify in the field by looking for 'flashes' of color when rotated in sunlight. Commonly found in Canada (Labrador), Madagascar, Norway, Finland (Spectrolite variety), and Russia. Look for dark gray silicate rocks with a distinctive internal glow.